The present invention relates to a wet gate construction designed for advantageous use with a photographic strip film printer, e.g., a reduction printer. The purpose of such equipment can, to advantage, be the drafting of photographic strip film through a liquid-containing chamber defined between a pair of gate halves which are equipped with opposed and aligned, transversely spaced-apart optical windows, such as is proposed in the U.S. Ott U.S. Pat. No. 3,614,223 of Oct. 19, 1971. The present wet gate construction is an appreciable improvement upon that disclosed in that patent, and specifically in that it assures an appreciably greater efficiency in stripping the liquid within the gate assembly from the traveling film surfaces at the chamber exit end. This prior art patent depends solely upon evacuating equipment at the strip film exit end of the gate which has been found to demand very careful and costly fitting of opposed surfaces of the gate halves together to avoid undue leakage of the gate chamber, particularly at the exit end thereof. This is particularly true with respect to the film strip exit slot since it must be sufficiently wide enough to pass therethrough film strip splices without damage to these splices or adjacent sections of the film. Consequently, leakage is excessive and must be accommodated by elaborate and undesirably cost increasing collectors of such excessive leakage.
It is a general object of the present invention to overcome such problems by relatively simple and reliable film exit end leakage reducing means of the present invention.
A more specific object of the invention is to supplement the evacuating equipment at the film exit end with a set of opposed cooperating squeegee rollers which are biased toward each other preferably with resilient means that permit exit transport out therebetween of film strips of various thicknesses and lap joints thereof while maintaining snug contact of the film surfaces on its opposite sides by the opposed rollers.
A still further object of the invention is to utilize to advantage such a set of squeegee rollers at the top entrance end to simplify also the liquid seal thereat in supplement to the set thereof at the bottom exit end.
The present invention may be embodied to appreciable advantage in a wet gate assembly construction which includes a pair of complementary gate halves demountably fastened together to form between opposed faces thereof a through strip film path from a top entrance end down to a bottom exit end thereof. A pair of light-transmitting optical windows having substantially aligned transverse central axes respectively are fitted into one of a pair of opposed apertures separately formed in the gate halves with these windows located in transversely spaced-apart relation on opposite sides of the strip film path to define a chamber therebetween. Cooperative leakage blocking means are provided on the opposed faces of these gate halves along opposite sides of the windows which close the sides of the chamber efficiently. Transverse leakage blocking means are cooperatively provided on the entrance ends of the gate halves for preventing leakage up out of the gate assembly chamber while permitting strip film to be drafted down therethrough between the transversely spaced windows. Each of a pair of transverse manifolds is provided in one of the gate halves about its window with each manifold having means adapted to be connectable to a source of relatively pressurized liquid and provided with transversely spaced passage outlets communicating with the upper portion of the chamber. A pair of cooperating transverse squeegee rollers is provided with each rotatably mounted at the face of and by one of the gate halves below the window therein with at least an arcuate longitudinal zone of each roller extending laterally forward beyond the face of the gate half supporting it with the opposed arcuate longitudinal zones of the pair of rollers being biased toward longitudinal contact with each other. These squeegee rollers extend laterally to cooperating leaking blocking positions relative to the side leakage blocking means and in cooperative sealing relation with respect to each other for closure of the bottom of the chamber. Means define behind each of these rollers in the gate half supporting it a transverse open-face channel connectable to suction means for drawing off liquid from the chamber at these rollers while substantially blocking leakage therebelow.
In such a wet gate assembly the transverse leakage blocking means in the vicinity of the entrance ends of the gate halves to define the top of the liquid chamber advantageously may be in the form of a pair of transverse squeegee rollers with a first one mounted on the inner face of one gate half and the other on the opposed inner face of the other in cooperative relation to the first one. These top squeegee rollers are biased, preferably resiliently, toward each other, and they are located above the top liquid supply passage outlets. The ends of such top pair of squeegee rollers are mounted relative to the side leakage blocking means on the opposed faces of the gate halves along opposite sides of the windows in cooperative leak blocking relation.